There hasnt been many "Advanced" IK setup tutorials published to date. I figured its time I share my setup with the world.

This tutorial is for advanced users. Before reading this, please have a working knowledge of 3Dstudio Max's "New IK", or IK in general. In this tutorial you will be using 3D-Studio Max's "New IK", and Expressions to create 2 advanced setups.

This setup can be done in any package, including: Alias/Wavefront's Maya, and Softimage|3D. The tools are different, but the idea isnt.

"On with the show"

Note: As of writing this. Another talented 3D-Studio Max Animator, Michael B. Comet has recently posted a very useful IK setup tutorial, and it is very good. Be sure to check his out as well. Our setups are somewhat similar so feel free to cross reference his tutorial with mine if you have any difficulty understanding the setups

Lets meet the Skeletons.

IK Setup Type 1

Well here she is... Meet IK Setup Type 1. Lets look at her for a moment and study her structure.
As you can see her skeleton is designed for a normal bipedal humanoid creature. The chain for the legs and foot are a single chain. Notice the grey chains on the feet. These chains are not her feet. Instead they are seperate chains that provide controls for the forward kinematic motion of the toe, and heal.

It's also used to position the feet when animating. This control allows the animator to use both the Inverse Kinematics of the foot, and Forward Kinamation. This chain I will refer to as the "Boot". In a sense thats what it is. If you dont understand the boot concept yet, you will by the end of this tutorial. For now know that this boot is not part of the leg and foot chain, and that the root to toe chain is all one chain of bones. The boot concept is used in both setups, Type 1 and Type 2.

The dummies are the animation controls. All animation is to be done using these dummies. Nevermind the blue End Effectors in the scene.

(Note Joint limits are hidden in this image, but they are setup)

PROS:

This skeleton allows you to have all the controll you'll need to animate.

Allows FK and IK animation on feet/toes

Allows for controll of the upvector plane of the leg chain. This allows the animator to orient the knee as desired. (only in a Type 2 setup)

CONS:

Knee position does not stay "forward" when rotating the hip controller during a walk cycle. By forward I mean staying inline with the foot. It will turn with the hip. Other wise the knee behavior is correct. The solution to this is to not rotate the hips on the Z axis during a walk cycle.However there is a control to correct this by manual FK animation. Since Max doesnt have an Upvector/Pole vector constraint, this is the best one can do. (only in a type 2 setup)